DE2225015A1 - Color stabilized alkanolamines - Google Patents

Description

Patent attorneys Dipl. - Ing.F. Weig .ίμανν,

DiPL.-l ^ G. H. Teickmann, Dipl.-Phys. Dr. K. Fincke Dipl.-Ing. F. A. Weickmann, Dipl.-Chem. B. Huber

8 MUNICH 86, POST BOX 860 820

MÖHLSTRASSE 22, NUMBER 48 39 21/22

(983921/22)

H / Kn OASE: 15,485-P

THE DOV / CIIEHICAI, COMPAlJY, Midland, Michigan / USA 929 Eaet Main Street

"I color stabilized alkanolamines"

The invention relates to alkanolamines against undesirable Parchment are stabilized.

Alkanolamines v / earth usually by reaction of a Alkylene oxide made with ammonia or an amine; the The present invention relates to the alkanolamines so produced.

Prically prepared alkanolamines are clear or near-clear v / ^ nnerkXare liquors. However, if they have a certain Stand ly-ng time, so they generally darken and take t; a yellow or yellow-green color. This obscurity occurs

BATH ORIGINAL ₂

209850/1215

regardless of whether the alkanolamine is exposed to daylight or sunlight or not and regardless of whether it is is closed off from the atmosphere or not. The dark is generally accelerated when the alkanolamine stored in an iron container (such as a steel barrel). The obscurity of the alkanolamine is in many Cases undesirable, which depends on the intended use. Triethanolamine for example is being used on a large scale used in the cosmetic market and must therefore be largely color-free in order for it to be accepted by the trade.

Alkali metal borohydrides have been used both for decolorizing and for stabilizing Alkanolamineη, cf. US Patents 3,207,790 and 3,159,276, the latter describes the stabilization of ethanolamines against Discoloration.

Boric acid, alkyl boric acid, hydrocarbon borates and others such organoboron compounds have been used to stabilize aromatic amines, see U.S. Patent 2,422,503.

In the present case it was found that the alkali and alkaline earth metal borates and alkanolamine esters of boric acid particularly effective in inhibiting the discoloration of alkanolamines. Such borates are referred to below as borate inhibitors.

The alkali and alkaline earth metal borates are preferred.

Suitable for the purposes of the present invention alkali and alkaline earth metal borates can any of the known Klaaoe auo the Alkall- and alkaline earth metal borates go wi-ihlt; will. The lithium, ilatriuir., Potassium, Mr.gneiJiuin and Kfilaium borates are the most common and can be

209850/1215 bad original

used in anhydrous or l ^ drated form. Examples of suitable borates of this type include lithium and potassium tetraborate, lithium and potassium tetraborate, liatrium tetraborate decahydrate (borax, Na ₂ BO ₇ * 10 HpO), sodium tetraborate pentahydrate, sodium tetraborate (anhydrous borax), sodium pentaborate, HpO octahydrate [Mg (BO ₂ ) ₂ · 8H ₂ O], calcium diborate (CaB ₂ O.) and calcium _{triborate heptahydrate (Ca 2} BrO ₁ -1.7HpO). The borates as a class are described by PA Cotton and G. Wilkinson in "Advanced Inorganic Chemistry", 2nd Edition, Interscience Publishers (1966), pages 264-266. Sodium and potassium borates (especially sodium borates) are preferred.

The alkanolamine esters of boric acid are a known class of compounds. Any member of the class can be used in the present case. Such esters are described, for example, by HC Brown et al., JACS 7.3, 2808 (1951; H. Steinberg et al., Ind. Eng. Chem. 49., 174 (1957), "Organoboron Chemistry", Volume 1 by Steinberg, Interscience Publishers , II.Y. (1964), Chapters 4 and 5, pp. 132-134, especially pp. 232-245, They can be conveniently prepared by reacting an alkanolamine with boric acid, generally in the presence of a suitable solvent Preferred esters are those which are formed by reacting boric acid with the alkanolamine to be stabilized, for example the ester formed by reacting triethanolamine with boric acid would be a preferred inhibitor for triethanolamine, etc. Other such esters are those formed by reacting boric acid with ethanolamine, diethanolawin , Mono-, di- or tri-isopropanolamine, mono-, di- or tri-butanolamine, II (2-hyaroxyethyl) propylamine, N, IT-di- (2-hydroxyethyl) ethylamine, IJ ₁ K-Di - (2-hydro; -: ypropyl) -butylamine formed ester.

BATH ORIGINAL

209850/1215

The borate inhibitors according to the invention are mixed with the alkanolamines in a small but effective amount to prevent color formation in the alkanolamines}! to prevent. In general, borate amounts of up to about 4 G-ew.-yo, based on the alkanolamine, are sufficient, but more can be used in special cases if desired. Borate inhibitor levels of from about 0.004 $> to about 0.02 ^e ß> are preferred in the typical case.

The borate inhibitors according to the invention are generally soluble in the alkanolamines. The ease with which they dissolve in the alkanolamines will of course vary depending on the particular borate and the particular alkanolamine. In technical operations it is therefore advantageous to dissolve the borate in an aliquot portion of the alkanolamine and then add this solution to the bulk of the alkanolamine to be stabilized. In cases where the borate is substantially insoluble in alkanolamine borate is mixed amine as finely divided solids in the alkanol. "

As already mentioned above, the alkanolamines stabilized according to the invention are those which are usually produced by reacting an alkylene oxide with ammonia or an Awin. Those which are produced by reacting ethylene oxide, propylene oxide and / or butylene oxide with ammonia or an amine are particularly important industrially. The invention relates to all such alkanolamines, in particular ethanolamines and Propanolanine that prepared by reacting ethylene oxide or propylene oxide with ammonia v / earth (for example, mono- t di- and / or triethanolamine and mono-, Diunu / or tripropanolamine).

BAO OfllGtNAL

209850/1215

example

1 to 12

The following examples are accelerated aging tests which serve to further explain the invention. In each example, day borate was dissolved in 40.0 g of alkanolamine and placed in a sealed glass flask under nitrogen. The flask and contents were then heated ^{at 120 ° C. for 24 hours.} The color of the alkanolamine was determined before and after heating. The results of a series of experiments are briefly sums in Table I below. Experiments 1 to 15 were carried out using different triethanolamine samples. In each case a comparison standard was subjected to the same conditions; this comparative sample is the same trialkanolarjin sample, but without an inhibitor. The color is given in APIIA units.

A. Inhibitor TABLE I. Color on BATH ι end attempt A. (Conc.) Color on B. Beginning B. inhibited Ver B. sample equal C. (0.004 io) sample C. (0.01 ^v / o) 30th 43 50 1 D. (0.002 f,) 30th 30th 50 IV) E. (0.01% ) 30th 47 50 3 F. (0.01 #) 20th 20th 35 4th F. (0.01 #) ^ 70 70 120 5 G (0.02 '$) 20th 20th 40 6th (0.03 #) 5 5 20th 7th (0.01 </ i) 10 10 60 3 (0.005 ^c / *). 35 35 60 9 . (0.02 0) / ■■> '-> ν, ".- 30 35 50 10 (0.02 i ») 30th 30th 50 11 209 5 5 20th 12th 850/1215 ORIGINAL

Inhibitor "A" =

Tiatrium naborate tetrahydrate (HaBOp

Inhibitor "B ¹¹ = Iatriurrtetraborate decahydrate (Na ₂ B ^

Inhibitor "C" = liatric pentaborate decahydrate

Inhibitor "D" = potassium tetraborate decahydrate

.1

Inhibitor "E" = potassium pentaborate decahydrate (K ₂ B ₁₀ O ₁ ^ iOH ₂ O)

Magnesia orthoborate (Mg ^ B ₂ Og).

Inhibitor "l x ¹ " =

Inhibitor "S" =

ITatriuropentaborate decahydrate and was called 20% strength by weight solution in diethanolamine added.

example

13 to 16

Four 208 liter servings of a non-stabilized triethanolorriins (of at least 98% purity, whereby it the rest is mainly diethanolamine.) were filled in 208 liters of phosphated steel register. Three of the samples filled in passports were then added by adding 0.03% by weight, based on the total weight,

(a) sodium metaborate tetrc hydrate,

(b) sodium tetraborate decahydrate and

(c) Ijatriurapentaborate decahydrate

color stabilized. The fourth pass, the unstabilized one Containing material was used as a comparative sample. All registerers were then kept under ambient conditions for 4 weeks stored. The color of the material stored in this way was determined; the color of the stabilized (inhibited) I-material remained unchanged, while the sample of the comparative sample of the original Ft! roe of --Ό ΑΡΙίΑ units up to 25 to 27

BATH ORIGINAL

209850/1215

APjIA ~ unity darkened. Aliquots from each stored The material was subjected to the accelerated aging test, as used in Examples 1 to 12 above became; the perbe of the stabilized material remained unchanged, while the comparative sample was based on 45 APHA units darkened.

example

1? until 25

The accelerated aging test mentioned in Examples 1 to 12 was used and the J stability of others was used Alkanolamines evaluated in the presence of the borates according to the invention. The results are summarized in Table II:

Alkanol TABLE II (Conc.) Color on Verse. amine Inhibitor (0.02 #) Beginning HEA (0.05 io) 10 17th MEA A. (0.04 io) 10 18th DEA B. (0.01 io) 10 19th DEA A. (0.03 io) 10 20th HIPA B. (o, oi io) 5 21st DIPA B. (0.05 io) 10 22nd DIPA A. (0.03 io 10 23 IEEDA B. (0.05 io) 15th 24 Dl-IEA A. 30th 25th B.

Parbe in the end

inhibit Ver th sample equal sample 10 40 10 40 10 25th 10 25th 5 30th 10 30th 10 30th 15th 25th 30th 60

IDiA is ionoethanolanine; DEA is diethan ο lamin;

MIPA int I-ionoisopropanolarain; DIPA is diisopropanolanine;

ISDA is li- (2 «Hydrozyäthyl) -äthylenäianin and

DI-LSA let JT, IT-dimethylethanolanine;

The inhibitors "A", "3" and "0" _B ± - _a & the ira connection 3

Table I grated,

BATH

209850/1216

b'g! games 26th until 28

The solenoid described in Examples 1 to 12 was used. nigto aging tea applied, with the exception that one Strips of wrought iron with an approximate surface area of 19.4 cm in the test liquid side. The color stability of mono & thanolaoin and monoisopropanolanine was assessed in the presence of the borates according to the invention. The results are shown in Table III · Bei the inhibitors "A" and "B" are the gloiohen, which are mentioned in connection with table I *

Alkanol
amine U) ABELIiB III Color on
Beginning colour at the end ore. KSA
MEA
MIPA Inhibitor
(Conc.) 10
10
5 inhi «beer
th sample Ver
equal
sample A (0.03 0)
B (0.05 W
A (0.04 t) 40
40
40 160
160
130 26th
27
26th

Example e

29 to 30

Using the bit 12 described in Examples 1 accelerated aging tests, the color stability of iriethanolarain (! IEA) in the presence of the ΤΕΛ-Eger of boric acid was determined at two concentrations. The results are summarized in table | V *

209850/1215

Verse.

29
30th

Inhibitor

(Κ.ΟΏΖ,)

0.05 0.15

TABLES IV

Color in the beginning

20th
20th

Color in the end

inhibited

Sample same sample

20th
20th

60 60

The above TEA ester of boric acid was prepared by adding 110 grams of boric acid (1.77 moles) to 263 grams of TEA (1.77 moles) in 250 ml of toluene and heating the mixture at reflux temperature until the reaction was complete. The by-product V / ater was essentially removed as a V / ater / ToliiOl azeotrope as it was formed; approximately 96 g / water was collected. The desired reaction product (276 g) crystallized out of the reaction mixture on cooling and was separated off by filtration. The white crystalline product melted at 234 to 237 ⁰ C (literature data: 235 to 237 ⁰ O).

209850/1215

Claims (1)

- ίο - PATENT CLAIMS 1. «Hasse, consisting of at least one alkanolamine, which tends to discolour during storage, characterized in that it contains a sufficient amount of at least one alkali or Alkaline earth metal borates or an alkanolamine ester containing boric acid to discolour the alkanolamine to inhibit. Process for preventing discoloration, characterized in that the alkanolamine is given a small amount, but sufficient to inhibit the discoloration, of at least one alkali metal or alkaline earth metal borate or an alkanolamine ester of boric acid
incorporated. BATH ORIGINAL
209850/1215